{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-46428",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-05-13T22:18:22.830Z",
        "datePublished": "2026-07-20T15:37:58.396Z",
        "dateUpdated": "2026-07-21T15:49:36.495Z"
    },
    "containers": {
        "cna": {
            "title": "lettre has TLS hostname verification disabled when using Boring TLS backend",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-295",
                            "lang": "en",
                            "description": "CWE-295: Improper Certificate Validation",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "LOW",
                        "subIntegrityImpact": "LOW",
                        "subAvailabilityImpact": "NONE",
                        "baseScore": 9.1,
                        "baseSeverity": "CRITICAL",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N",
                        "version": "4.0"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53"
                },
                {
                    "name": "https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35"
                },
                {
                    "name": "https://github.com/lettre/lettre/releases/tag/v0.11.22",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/lettre/lettre/releases/tag/v0.11.22"
                },
                {
                    "name": "https://rustsec.org/advisories/RUSTSEC-2026-0141.html",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://rustsec.org/advisories/RUSTSEC-2026-0141.html"
                }
            ],
            "affected": [
                {
                    "vendor": "lettre",
                    "product": "lettre",
                    "versions": [
                        {
                            "version": ">= 0.10.1, < 0.11.22",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-07-20T15:37:58.396Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "lettre is a a mailer library for Rust. Starting in version 0.10.1 and prior to version 0.11.22, an inverted-boolean bug in lettre's `boring-tls` integration silently disables TLS hostname verification for callers using the default (strict) configuration. An on-path attacker presenting any chain-valid certificate for any domain can intercept SMTP submission, including PLAIN/LOGIN credentials and message contents, against any lettre user built with the `boring-tls` feature. Other TLS backends (`native-tls`, `rustls`) are unaffected. Version 0.11.22 patches the issue."
                }
            ],
            "source": {
                "advisory": "GHSA-4pj9-g833-qx53",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "references": [
                    {
                        "url": "https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53",
                        "tags": [
                            "exploit"
                        ]
                    }
                ],
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-07-21T15:48:51.405919Z",
                                "id": "CVE-2026-46428",
                                "options": [
                                    {
                                        "Exploitation": "poc"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "total"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-07-21T15:49:36.495Z"
                }
            }
        ]
    }
}